The invention relates to a propulsion device for power machines or tools stationed along continuous flow machines production lines, in particular as adopted in the manufacture of iron and steel products, such as rolled bars. Such devices serve specifically, though by no means exclusively, to generate the following movement of `flying` machines units or equipment used to effect operations such as shearing, cross-cutting and punching, etc., on part-machined work generally, which cannot be allowed to remain stationary in a fixed position due to its very nature or shape, or to the operating requirements of production media installed up-line, but must be kept moving steadily forward (generally along a straight path). Devices of the type in question operate to a set cycle that must be completed normally within a significantly short space of time, and will include a succession of essential steps: 1) hard acceleration, serving to take the machine or equipment at high speed from a stationary at-rest position up to a velocity approaching that of the work moving along the line; 2) stabilization and alignment, whereby the machine or equipment gains a velocity identical to that of the line and the tool is positioned accurately in readiness to operate; 3) operation of the machine or equipment proper, following the moving line at identical velocity for as long as is necessary to effect the machining stroke and retract the tool; 4) hard deceleration, whereby the machine is slowed up to a complete standstill at the installed travel limit; 5) return of the machine or equipment to the original at-rest position in readiness for the next cycle.
The implemention of a cycle as outlined above in steel production, and in metallurgical processes generally, involves a number of problems of which most are connected with the particular features and hostile nature of the operating environment. Prior art methods have failed thus far to provide a satisfactory response to these problems. For example, conventional propulsion devices which utilize clutch-brake mechanisms combine positive features such as accuracy in synchronization, i.e. obtaining identical velocity of the tool and the work, with negative factors such as poor alignment and heavy wear, which severely jeopardizes the dependability of the clutch and brake assemblies. Other conventional propulsion devices utilize fluid power, hydraulic or pneumatic. Whilst the actuator is essentially simple in such devices (an ordinary cylinder), synchronization between the velocities of tool and work nonetheless require complicated mechanisms, and the fluid control systems tend to be low on dependability due to the hostility of the operating environment.
Similarly, the prior art embraces electromechanical systems utilizing a geared electric motor coupled to a rack-and-pinion type drive, which apparently possess all the features necessary for faultless implementation of the propulsion cycle in question (fine adjustment of drive parameters, good levels of machining accuracy, good general flexibility), though in practice, serious limitations are found to exist precisely in iron and steel manufacture; more exactly, the rack-and-pinion drive, essential to ensuring a rigid connection between the geared motor and the moving assembly, becomes subject to early wear as a result of operating in environments that are heavily laden with oxides, calamines and swarf.
Limitations of an even more serious nature are encountered with chain-driven propulsion devices; such devices are in fact unable to accommodate sharp acceleration and deceleration, and prone to elongation, the damaging consequence of which is to jeopardize correct synchronization of the tool and work velocities as described above. Accordingly, the object of the present invention is to overcome the various drawbacks and shortcomings of the prior art as described above.